High-pressure liquid chromatography systems, such as high performance liquid chromatography (HPLC) and ultra performance liquid chromatography (UPLC) systems, typically employ injection valves having a rotary shear seal. A force of several hundreds of pounds or more is applied between the rotor and stator to seal against pressures that can exceed 15,000 psi. The force is maintained while the rotor rotates between valve switch positions, thereby placing stringent requirements on the quality of the sealing surfaces. The injection valves are typically designed for tens of thousands of cycles without excessive wear and leakage. Liquid chromatography instrument manufacturers anticipate future instruments will require sealing pressures of injection valves to exceed 18,000 psi and still provide tens of thousands of cycles. The trend to greater operating pressures may be beyond the capabilities of design and materials of conventional injection valves. Increasing the compressive load may suffice to achieve higher sealing pressures, but this approach can result in faster wear of the rotor and stator, with an associated increased leakage and reduced valve lifetime.